191564257 has 2 divisors, whose sum is σ = 191564258. Its totient is φ = 191564256.

The previous prime is 191564239. The next prime is 191564287. The reversal of 191564257 is 752465191.

191564257 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 165920161 + 25644096 = 12881^2 + 5064^2 .

It is a cyclic number.

It is not a de Polignac number, because 191564257 - 2²³ = 183175649 is a prime.

It is not a weakly prime, because it can be changed into another prime (191564237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95782128 + 95782129.

It is an arithmetic number, because the mean of its divisors is an integer number (95782129).

Almost surely, 2^191564257 is an apocalyptic number.

It is an amenable number.

191564257 is a deficient number, since it is larger than the sum of its proper divisors (1).

191564257 is an equidigital number, since it uses as much as digits as its factorization.

191564257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75600, while the sum is 40.

The square root of 191564257 is about 13840.6740081544. The cubic root of 191564257 is about 576.4630738339.

The spelling of 191564257 in words is "one hundred ninety-one million, five hundred sixty-four thousand, two hundred fifty-seven".